Polyphenols have gained increasing interest due to their protective effects on human health. In particular, polyphenols were shown to reduce the risk of chronic diseases such as cardiovascular diseases and cancers. Therefore, polyphenols may prove useful in functional foods or as medicines. Their anti-oxidant effect may further lead to applications in cosmetics.
Polyphenols are traditionally known from cocoa beans, but other plants such as sage, green tea, other cocoa products, many other plants and also contain considerable amounts of these natural substances. Due to the increasing demand for natural antioxidants and other health-related products, there is a constant need to explore new raw materials.
Recent studies have shown that the effect of polyphenols varies with their degree of polymerisation (dp). For example, tetramers of procyanidins (dp=4), a special class of polyphenols, proved most effective for ACE inhibition in human umbilical vein endothelial cells (Ottaviani et al., Biochimie 88, 2006, 359-265), tetramers, pentamers and hexamers of procyanidins showed a high inhibitory effect of ACE in isolated rabbit lung cells (Actis-Goretta et al., FEBS Letters 555, 2003, 597-600), and protection from oxidation increases with increasing chain length of procyanidin oligomers (from dp=1 to dp=5) in model liposomes (i.e., procyanidin pentamers show a better liposome protection than procyanidin monomers (Lotito et al., Biochemical and Biophysical Research Communications 276, 2000, 945-951)). Moreover, pentamers of procyanidins inhibited tyrosine kinase ErbB2 expression and decreased cell proliferation in human aortic endothelial cells (Kenny et al., Experimental Biology and Medicine 229, 2004, 255-263). Monomers, dimmers, and trimers of procyanidins, in contrast, have different pharmacokinetic profiles compared to oligomers such as tetramers, pentamers and hexamers of procyanidins.
Osman et al., Food Chemistry 86, 2004, 41-46, describe that consumption of foods and beverages rich in phenolic content can reduce the risk of heart disease, slowing the progression of atherosclerosis by acting as antioxidants towards low-density lipoprotein. Osman et al. also prepared extracts of cocoa leaves and determined their antioxidation potential. However, Osman et al. did not consider procyanidins; it also appears the total polyphenol content obtained by the process applied by Osman et al. was poor.
In JP 2000-060485A, extracts were obtained by extraction with water/hydrochloride for 30 minutes at 90° C. However, procyanidins and their composition were not characterized; it also appears that the total procyanidin content was low. Extraction of procyanidins from cocoa beans is described in U.S. Pat. No. 6,627,232.
However, none of the processes described in the prior art allows regulation of the relative amounts of monomers, dimmers, and trimers in comparison to higher oligomers of procyanidins that show different physiological properties. Additionally, the oligomers appear to have a significantly increased astringent effect as compared to the moners, dimers, and trimers. Moreover, some plant material contains considerable amounts of theobromine that also may cause an increase in bitterness. Processes allowing a reduction of theobromine content would thus be advantageous when plant extracts are used in food.
The challenge of providing a process for preparing polyphenol containing compositions rich in polyphenol oligomers or rich in polyphenol monomers, dimers, and trimers has not yet been solved. Processes that allow the adjustment of the relative content of monomers, dimers and/or trimers and higher procyanidin oligomers (dp=4 to 6) and at the same time reduce the content of theobromine were not known before the present invention.
The present invention provides a process for preparing polyphenol containing compositions rich in polyphenol oligomers and compositions rich in polyphenol monomers, dimers and trimers. The present inventors have developed a process for preparing polyphenol containing compositions that allows for specific adjustment of the content of monomers, dimers and/or trimers and higher procyanidin oligomers. Moreover, present invention significantly reduces the content of theobromine.